// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// See www.openfst.org for extensive documentation on this weighted
// finite-state transducer library.
//
// Google-style flag handling declarations and inline definitions.

#ifndef FST_LIB_FLAGS_H_
#define FST_LIB_FLAGS_H_

#include <cstdlib>

#include <iostream>
#include <map>
#include <set>
#include <sstream>
#include <string>

#include <fst/types.h>
#include <fst/lock.h>

#include "gflags/gflags.h"
#include "glog/logging.h"

// FLAGS USAGE:
//
// Definition example:
//
//    DEFINE_int32(length, 0, "length");
//
// This defines variable FLAGS_length, initialized to 0.
//
// Declaration example:
//
//    DECLARE_int32(length);
//
// SET_FLAGS() can be used to set flags from the command line
// using, for example, '--length=2'.
//
// ShowUsage() can be used to print out command and flag usage.

// #define DECLARE_bool(name) extern bool FLAGS_ ## name
// #define DECLARE_string(name) extern std::string FLAGS_##name
// #define DECLARE_int32(name) extern int32 FLAGS_ ## name
// #define DECLARE_int64(name) extern int64 FLAGS_ ## name
// #define DECLARE_uint64(name) extern uint64 FLAGS_##name
// #define DECLARE_double(name) extern double FLAGS_ ## name

template <typename T>
struct FlagDescription {
    FlagDescription(T *addr, const char *doc, const char *type,
                    const char *file, const T val)
            : address(addr),
              doc_string(doc),
              type_name(type),
              file_name(file),
              default_value(val) {}

    T *address;
    const char *doc_string;
    const char *type_name;
    const char *file_name;
    const T default_value;
};

template <typename T>
class FlagRegister {
public:
    static FlagRegister<T> *GetRegister() {
      static auto reg = new FlagRegister<T>;
      return reg;
    }

    const FlagDescription<T> &GetFlagDescription(const std::string &name) const {
      fst::MutexLock l(&flag_lock_);
      auto it = flag_table_.find(name);
      return it != flag_table_.end() ? it->second : 0;
    }

    void SetDescription(const std::string &name, const FlagDescription<T> &desc) {
      fst::MutexLock l(&flag_lock_);
      flag_table_.insert(make_pair(name, desc));
    }

    bool SetFlag(const std::string &val, bool *address) const {
      if (val == "true" || val == "1" || val.empty()) {
        *address = true;
        return true;
      } else if (val == "false" || val == "0") {
        *address = false;
        return true;
      }
      else {
        return false;
      }
    }

    bool SetFlag(const std::string &val, std::string *address) const {
      *address = val;
      return true;
    }

    bool SetFlag(const std::string &val, int32 *address) const {
      char *p = nullptr;
      *address = strtol(val.c_str(), &p, 0);
      return !val.empty() && *p == '\0';
    }

    bool SetFlag(const std::string &val, int64 *address) const {
      char *p = nullptr;
      *address = strtoll(val.c_str(), &p, 0);
      return !val.empty() && *p == '\0';
    }

    bool SetFlag(const std::string &val, uint64 *address) const {
      char *p = 0;
      *address = strtoull(val.c_str(), &p, 0);
      return !val.empty() && *p == '\0';
    }

    bool SetFlag(const std::string &val, double *address) const {
      char *p = nullptr;
      *address = strtod(val.c_str(), &p);
      return !val.empty() && *p == '\0';
    }

    bool SetFlag(const std::string &arg, const std::string &val) const {
      for (const auto &kv : flag_table_) {
        const auto &name = kv.first;
        const FlagDescription<T> &desc = kv.second;
        if (arg == name) return SetFlag(val, desc.address);
      }
      return false;
    }

    void GetUsage(
            std::set<std::pair<std::string, std::string>> *usage_set) const {
      for (auto it = flag_table_.begin(); it != flag_table_.end(); ++it) {
        const auto &name = it->first;
        const FlagDescription<T> &desc = it->second;
        std::string usage = "  --" + name;
        usage += ": type = ";
        usage += desc.type_name;
        usage += ", default = ";
        usage += GetDefault(desc.default_value) + "\n  ";
        usage += desc.doc_string;
        usage_set->insert(make_pair(desc.file_name, usage));
      }
    }

private:
    std::string GetDefault(bool default_value) const {
      return default_value ? "true" : "false";
    }

    std::string GetDefault(const std::string &default_value) const {
      return "\"" + default_value + "\"";
    }

    template <class V>
    std::string GetDefault(const V &default_value) const {
      std::ostringstream strm;
      strm << default_value;
      return strm.str();
    }

    mutable fst::Mutex flag_lock_;        // Multithreading lock.
    std::map<std::string, FlagDescription<T>> flag_table_;
};

template <typename T>
class FlagRegisterer {
public:
    FlagRegisterer(const std::string &name, const FlagDescription<T> &desc) {
      auto registr = FlagRegister<T>::GetRegister();
      registr->SetDescription(name, desc);
    }

private:
    FlagRegisterer(const FlagRegisterer &) = delete;
    FlagRegisterer &operator=(const FlagRegisterer &) = delete;
};


#define DEFINE_VAR(type, name, value, doc)                                \
  type FLAGS_ ## name = value;                                            \
  static FlagRegisterer<type>                                             \
  name ## _flags_registerer(#name, FlagDescription<type>(&FLAGS_ ## name, \
                                                         doc,             \
                                                         #type,           \
                                                         __FILE__,        \
                                                         value))

// #define DEFINE_bool(name, value, doc) DEFINE_VAR(bool, name, value, doc)
// #define DEFINE_string(name, value, doc) \
//   DEFINE_VAR(std::string, name, value, doc)
// #define DEFINE_int32(name, value, doc) DEFINE_VAR(int32, name, value, doc)
// #define DEFINE_int64(name, value, doc) DEFINE_VAR(int64, name, value, doc)
// #define DEFINE_uint64(name, value, doc) DEFINE_VAR(uint64, name, value, doc)
// #define DEFINE_double(name, value, doc) DEFINE_VAR(double, name, value, doc)


// Temporary directory.
DECLARE_string(tmpdir);

void SetFlags(const char *usage, int *argc, char ***argv, bool remove_flags,
              const char *src = "");

#define SET_FLAGS(usage, argc, argv, rmflags) \
google::ParseCommandLineFlags(argc, argv, true)
// SetFlags(usage, argc, argv, rmflags, __FILE__)

// Deprecated; for backward compatibility.
inline void InitFst(const char *usage, int *argc, char ***argv, bool rmflags) {
  return SetFlags(usage, argc, argv, rmflags);
}

void ShowUsage(bool long_usage = true);

#endif  // FST_LIB_FLAGS_H_
